chore: add tests

lib/report.js

@@ -100,6 +100,16 @@ class Report {
     return this._allCoverageFiles
   }
 
+  /**
+   * Returns source-map and fake source file, if cached during Node.js'
+   * execution. This is used to support tools like ts-node, which transpile
+   * using runtime hooks.
+   *
+   * Note: requires Node.js 13+
+   *
+   * @return {Object} sourceMap and fake source file (created from line #s).
+   * @private
+   */
   _getSourceMap (v8ScriptCov) {
     const sources = {}
     if (this.sourceMapCache[`file://${v8ScriptCov.url}`]) {

test/fixtures/ts-node-basic.ts

@@ -0,0 +1,34 @@
+export interface FooOptions {
+  x: number;
+}
+
+class Foo {
+  x: number;
+  constructor (options: FooOptions) {
+    this.x = options.x ? options.x : 99
+    if (this.x) {
+      console.info('covered')
+    } else {
+      console.info('uncovered')
+    }
+    this.methodC()
+  }
+  methodA (): number {
+    console.info('covered')
+    return 33
+  }
+  /* c8 ignore next 3 */
+  methodB () {
+    console.info('uncovered')
+  }
+  private methodC () {
+    console.info('covered')
+  }
+  methodD () {
+    console.info('uncovered')
+  }
+}
+
+const a = new Foo({x: 0})
+const b = new Foo({x: 33})
+a.methodA()

test/integration.js

@@ -311,4 +311,20 @@ describe('c8', () => {
       })
     })
   })
+
+  describe('ts-node', () => {
+    beforeEach(cb => rimraf('tmp/source-map', cb))
+
+    it('reads source-map from cache, and applies to coverage', () => {
+      const { output } = spawnSync(nodePath, [
+        c8Path,
+        '--exclude="test/*.js"',
+        '--temp-directory=tmp/source-map',
+        '--clean=true',
+        './node_modules/.bin/ts-node',
+        require.resolve('./fixtures/ts-node-basic.ts')
+      ])
+      output.toString('utf8').should.matchSnapshot()
+    })
+  })
 })

test/integration.js.snap

@@ -219,3 +219,18 @@ All files  |    83.33 |    85.71 |       60 |    83.33 |                   |
 -----------|----------|----------|----------|----------|-------------------|
 ,"
 `;
+
+exports[`c8 ts-node reads source-map from cache, and applies to coverage 1`] = `
+",covered
+covered
+covered
+covered
+covered
+------------------|----------|----------|----------|----------|-------------------|
+File              |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
+------------------|----------|----------|----------|----------|-------------------|
+All files         |    88.24 |     87.5 |       80 |    88.24 |                   |
+ ts-node-basic.ts |    88.24 |     87.5 |       80 |    88.24 |       12,13,28,29 |
+------------------|----------|----------|----------|----------|-------------------|
+,"
+`;